Binary data, that is, arbitrary data using unrestricted byte values, is frequently transported in
text data formats where the syntax limits the available byte values. (Examples: Binary data in SMTP
emails and in XML.) There are commonly used encodings for representing binary data in text; they map
binary values to a small repertoire of characters that is available in almost all legacy codepages.
Unicode presents an incentive and an opportunity for efficient encoding of binary data by using a
larger repertoire of characters, resulting in a more efficient encoding than common methods.